Hybrid utility vehicles such as grass mowing machines have electric motor and attendant control devices. For example, grass mowing machines may have several controllers. Variable speed and direction are required features of electric motors used in these machines, and the controllers used to achieve these features typically generate substantial heat. The heat must be dissipated to prevent damage to the controller and its components. For example, the heat may be dissipated by providing cooling fins, or heat sinks, on the controller packages. See, for example, U.S. Pat. No. 6,377,462, which is an example of a heat sink for an electronic controller. Cooling fins or heat sinks dissipate heat by allowing ambient air to pass over the fins as the vehicle moves around.
However, heat sinks and cooling fins have several disadvantages. For example, if the vehicle is moving slowly, or not at all, there is little air flow across the fins. Also, since the fins must have access to ambient air, the controllers are typically mounted in an exposed location. These electronic devices are susceptible to failure caused by moisture incursion, and so must be adequately sealed to block the moisture. Additionally, sealing the controllers is more difficult because the machines are normally washed thoroughly after each use by high pressure or low pressure, high volume water streams.
Hybrid grass mowing machines also may have several batteries used to store power. Batteries may have internal heat buildup, and can be subject to unacceptable discharge rates due to internal heat buildup. As a result, battery temperatures must be controlled.
It would be desirable to dissipate heat to prevent damage to electronic controllers and batteries in grass mowing machines. It would be desirable to provide sufficient cooling of electronic controllers and batteries without exposing those components to moisture incursion. It would be desirable to provide sufficient cooling of electronic controllers and batteries even if the grass mowing machine remains stationary. It would be desirable to mount the controllers and batteries in easily accessible locations.